Describes the status of one or more instances, including any scheduled events.

Instance status has two main components:

System Status reports impaired functionality that stems from issues related to the systems that support an instance, such as such as hardware failures and network connectivity problems. This call reports such problems as impaired reachability.

Instance Status reports impaired functionality that arises from problems internal to the instance. This call reports such problems as impaired reachability.

Instance status provides information about four types of scheduled events for an instance that may require your attention:

Scheduled Reboot: When Amazon EC2 determines that an instance must be rebooted, the instances status returns one of two event codes: 'system-reboot' or 'instance-reboot'. System reboot commonly occurs if certain maintenance or upgrade operations require a reboot of the underlying host that supports an instance. Instance reboot commonly occurs if the instance must be rebooted, rather than the underlying host. Rebooting events include a scheduled start and end time.

System Maintenance: When Amazon EC2 determines that an instance requires maintenance that requires power or network impact, the instance status is the event code 'system-maintenance'. System maintenance is either power maintenance or network maintenance. For power maintenance, your instance will be unavailable for a brief period of time and then rebooted. For network maintenance, your instance will experience a brief loss of network connectivity. System maintenance events include a scheduled start and end time. You will also be notified by email if one of your instances is set for system maintenance. The email message indicates when your instance is scheduled for maintenance.

Scheduled Retirement: When Amazon EC2 determines that an instance must be shut down, the instance status is the event code 'instance-retirement'. Retirement commonly occurs when the underlying host is degraded and must be replaced. Retirement events include a scheduled start and end time. You will also be notified by email if one of your instances is set to retiring. The email message indicates when your instance will be permanently retired.

Scheduled Stop: When Amazon EC2 determines that an instance must be shut down, the instances status returns an event code called 'instance-stop'. Stop events include a scheduled start and end time. You will also be notified by email if one of your instances is set to stop. The email message indicates when your instance will be stopped.

When your instance is retired, it will either be terminated (if its root device type is the instance-store) or stopped (if its root device type is an EBS volume). Instances stopped due to retirement will not be restarted, but you can do so manually. You can also avoid retirement of EBS-backed instances by manually restarting your instance when its event code is 'instance-retirement'. This ensures that your instance is started on a different underlying host.

For more information about failed status checks, see TroubleshootingInstances with Failed Status Checks in the Amazon Elastic Compute Cloud UserGuide for Linux. For more information about working with scheduled events, see Working with an Instance That Has a Scheduled Event in the Amazon ElasticCompute Cloud User Guide for Linux.

http://docs.aws.amazon.com/AWSEC2/latest/APIReference/ApiReference-query-DescribeInstanceStatus.html